Conveyer belt for photographic printing machines



Nov. 28, 1950 E. NASSIMBENE 2,532,134

CONVEYER BELT FOR PHOTOGRAPHIC PRINTING MACHINES Filed Nov. 10, 1948 IN V EN TOR.

47' 7' ORA E Y Patented Nov. 28, 1950 CONVEYER BELT FOR PHOTOGRAPHIC PRINTING MACHINES Ernest Nassimbene, Denver, 0010., assignor to The Gates Rubber Company, Denver, 0010., a corporation of Colorado Application November 10, 1948, Serial No. 59,258

7 Claims.

This invention relates to photographic printing apparatus and more particularly to improvements in a conveyor and sealing sleeve for a type of dry developer.

In machines of the type referred to, the manuscript to be copied is fed into the machine in contact with a sheet of sensitized paper, passed by a station where it is exposed to light, and then developed as it passes over the perforate side of a tank which contains fumes such as ammonia fumes. The common expedient employed to convey the paper over the perforate side comprises an endless rubber belt trained over rolls disposed at the sides of the tank. This belt or sleeve is of uniform thickness having smooth surfaces on both sides or in some installations, is smooth on the side which contacts the rolls and ribbed on the side which contacts the paper. In either event it is made of natural rubber throughout which has heretofore been found to be the most desirable material to withstand the conditions to which it is subjected. One of the requirements of such a belt is that it have a high coefficient of friction on the inside thereof which contacts the rolls so that it will have optimum traction characteristics. While natural rubber is well adapted to satisfactorily satisfy this condition, a belt constructed of this material alone has certain disadvantages among Which are: rapid deterioration on the conveyor side resulting from heat and action of ammonia fumes therewith, and excessive coefficient of friction which causes wrinkling of the printed paper, and others which will hereinafter become apparent.

Another principal disadvantage of prior art belts is that adequate sealing between the belt and ammonia tank has not been achieved with the result that the ammonia fumes leak into the machine and thence into the room where the operator is located. The pungent characteristics of ammonia cause discomfort to the operator. If leakage is excessive, the operator may be overcome by the fumes. In an attempt to protect the operator, it is common practice to employ a ventilating fan for removing the fumes from the machine. This is partially effective in decreasing the hazards mentioned but the leakage itself is highly undesirable because leakage flow of the ammonia causes an uneven concentration of the ammonia within the tank with the result that all parts of the paper are not uniformly developed. Since a ventilating fan must necessarily produce a differential pressure to effect fiow, the leakage of ammonia is therefore increased over what it would be in the absence of a fan. Thus the fan,

in disposing of the fumes, actually increases the losses. It is apparent, therefore, that if leakage could be minimized, the operators working conditions would be improved, the ventilation requirements Would be minimized, an improved printed product would result, and, of course, there would be a saving in ammonia with its attendant lessened requirements for feeding the ammonia to the tank.

The smooth surface belt, previously mentioned, has two principal disadvantages, first, that being of natural rubber throughout, it is subject to rapid deterioration resulting from the heat given off by the ammonia chamber and the action of the ammonia; and, secondly, the high coefiicient of friction of natural rubber will not produce optimum feeding of the paper, wrinkling thereof often occurring. When these belts are used, it is common practice to apply talc thereto to reduce the frictional characteristics to achieve correct feeding of the paper. It is difficult to apply the exact quantity of talc and maintain the changed frictional characteristic which results, hence, it

is only a corrective measure and not a cure for this defect. In a further attempt to obviate these disadvantages, belts have been made which are ribbed on the side which feeds the paper. This reduces the tendency to wrinkle, but increases ammonia losses due to the channels formed by the ribs at the sides of the belt. Being of natural rubber, no improvement is effected so far as deterioration is concerned.

The principal object of the invention, therefore, is to provide a conveyor belt for printing machines which will have optimum characteristics of its various parts to perform the particular functions required thereby.

Another object is to provide a belt which will operate in a more efficient manner and have a greatly increased life of operation.

Another object is to minimize the leakage of ammonia from a printing machine, thus improving the machine, generally, by eliminating attendant disadvantages thereof which result from such leakage.

Another object is to provide a belt which will operate at minimum tension, track properly, have optimum traction characteristics with the paper, and also substantially eliminate loss of ammonia from the developing tank.

Another object is to provide a belt with improved abrasion resistant characteristics.

Another object is to provide a belt which has improved heat resistant characteristics.

Still further objects and salient features will become more apparent from a consideration of the description to follow, the appended claims, and the accompanying drawing, in which:

Figure 1 is a perspective view of a developing tank with the novel belt in engagement therewith, a portion of the tank being broken away to show the interior thereof; I

Figure 2 is a perspective view of the developing tank;

Figure 3 is a fragmentary plan view of the outside of the belt taken in the direction of arrow 3, Figure 1;

Figure 4 is a section taken on line 4-4, Figure 3;

Figure 5 is a section taken on line 5-5, Figure 3;

Figure 6 is a plan view of the inside surface of the belt;

Figure '7 is a section of the top of the tank and the belt in operative engagement therewith taken on line 1-1, Figure 1, the top flight of the belt being omitted; and

Figure 8 is an enlarged View of Figure 4.

Referring in detail to the drawing, there is shown in Figure 1 a conventional developing tank .l-ll having trained thereover the belt II which constitutes the subject of the invention. Tank i0 is closed at its sides and ends and the top is provided with a plurality of apertures 12 which expose the paper to be developed to the ammonia fumes in the tank, these aperture being within is power driven and the other an idler, and the bearings, at least on one roll, are made adjustable so that the axes of the rollers may be Varied relative to one another to adjust the tension in the belt and also the tracking position of the belt on the rollers. Since these details are conventional and well known illustration thereof has been omitted. I

The belt I I has a portion of its lower run or flight in contact with the convex upper perforate surface of the tank and the sensitized paper which has now been exposed to the manuscript to be copied is fed to the station between such flight and the tank by a suitable conveyor (not shown), to be developed by being exposed to the ammonia fumes, all as well understood in the art.

The belt, as best shown in Figures 3 and 8 has an inner portion of natural rubber which is substantially flat, but slightly roughened with a rag finish 21 (see Fig. 6) to be subsequently described. The opposite side 2| is formed of neoprene, and has a plurality of parallel ribs 22 which extend crosswise of the belt, but terminate somewhat short of the side edges thereof leaving a margin 23 along each side which is of uniform thickness, the outer surface of which is in the same plane as the top surfaces of the ribs, as best shown in Figure 5. Between these two portions i interposed one or more layers of woven fabric 2E, here shown as two layers, which may be disposed relative to one another as to warp and weft as desired, such as parallel to the rim of the belt or on the bias. However, a construction found especially effective is one wherein two relatively thin sheets of rubberized fabric are placed face to face with the warp in both sheets running lengthwise of the belt. These sheets are substantially at the center, or pitch line of the belt and only slightly below the bottoms of the grooves and ribs, about ten thousandths of an inch therebelow having been found satisfactory. This fabric construction differs from the prior art in that formerly the fabric sheets were much thicker and were bonded together by a thin layer of rubber. The natural rubber portion, the neoprene portion, and the fabric are integrally secured together by vulcanization. The ribs 22 are generally rectangular in section, a slight taper or draft being provided at the sides, the tops being fiat. About sixteen ribs to the inch of length of the belt have been found satisfactory, although this number may be made more or less as desired. The unribbed portions '23 are of a width to somewhat correspond to the width of the imperforated margins 13 of the tank to provide a seal therewith, as shown in Figure '7, thus preventing ammonia from escaping between marginal portions is of the tank and margins 23 of contact with these margins which thus seal the entire margin around perforations l2. Figure 7 shows the sealing engagement along a margin l3, the sensitized paper 25 being shown passing over the perforations E2, the distortion of the belt being shown exaggerated in order to show the paper which is normally quite thin.

The rag finish 2'! on the inside of the belt provides a very effective traction surface for the rolls to engage and thus prevent slippage therebetween. It may be formed by applying a nonadhering fabric of desired texture to the surface of side 26 during curing. After the belt is cured the fabric is removed leaving a surface finish on the belt which conforms to the irregularities of the fabric.

A belt made in the manner described has been found to have an operational life several fold of the previous belts made of natural rubber. With natural rubber in contact with the tank, heat produced by the developing tank produces polymerization, the rubber first becoming tacky, then brittle. After it becomes brittle, it loses its abrasion resistant characteristics and the edges of holes 52 of the tank cut into the surface of the deteriorated rubber filling the holes and, of course, destroying the belt. The neoprene side of the belt is more resistant to deterioration from heat, retains its ability to resist the abrasive action of the tank, has a lower coefficient of friction than natural rubber at all times during its life, which is desirable to achieve improved feeding without wrinkling of the paper. Coupled with the feature which produces longer life and improved feeding, it also substantially minimizes loss of ammonia.

Having described the invention what is claimed as new is:

1. In a' printing machine of the type having a vapor containing tank with imperforate marginal portions on the ends of a wall thereof and a perforate portion therebetween, and rolls at opposite sides of the tank, the improvement which comprises; an endless paper conveyor belt adapted to be trained about the rolls and over the wall, the belt being of imperforate rubber-like material having substantially parallel faces, the inner face being flat and adapted to engage the rolls, the outer face being adapted to engage the Wall, the outer face having a plurality of grooves therein forming ribs between the grooves, the ribs and grooves being transversely disposed to the edges of the belt, the grooves terminating inwardly of the belt edges providing margins of uniform thickness adjacent the edges of the belt, the belt being so proportioned to the wall that the grooves and ribs are substantially coextensive in length with the width of the perforate portion and the margins of the belt are adapted to overlie and contact the imperforate marginal portions of the tank to effect a gas seal thereat, the top surfaces of the ribs and the tank engaging surfaces of the margins lying substantially in the same plane, whereby the ribs may contact and convey apiece of paper over the perforate portion of the Wall, the ribs and marginal portions on the outer face being constructed of synthetic rubber.

2. A belt as defined by claim 1 wherein the synthetic rubber is a chloroprene polymer.

3. A belt as defined by claim 1 wherein the synthetic rubber is of a type having a lower coefficient of friction than natural rubber and a higher resistance to abrasion than natural ruboer after application of heat and ammonia thereto.

4. A belt in accordance with claim 1 wherein the side of the belt adjacent the inner face is constructed of natural rubber.

5. A belt in accordance with claim 4 including reinforcing fabric disposed between the natural rubber and synthetic rubber.

6. A paper conveyor device for use with printin machines, comprising; an endless belt having an inner side of natural rubber and an outer side of synthetic rubber, the inner side having a fiat face adapted to be trained about a pair of rolls, the outer side having a plurality of ribs extending transversely to the direction of movement of the belt, said ribs terminating inwardly of the side edges of the belt, providing margins with fiat faces adapted to engage spaced imperforate portions of a developing tank disposed between rolls, the tops of the ribs being substantially in the same plane as the faces of the margins, and fabric reinforcing means disposed between the natural rubber and the synthetic rubber.

7. A belt in accordance with claim 6 wherein the face of the inner side is roughened with a rag finish.

ERNEST NASSIMBENE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,948,332 Carter Feb. 20, 1934 2,194,833 Nassimbene Mar. 26, 1940 2,350,257 Steglich May 30, 1944 2,475,809 Sullivan et a1 July 12, 1949 FOREIGN PATENTS Number Country Date 729,107 France Apr. 19, 1932 

